This invention relates to locking pliers, and in particular to an improved locking pliers that is well-suited to apply large torques to a workpiece locked in the pliers.
Various types of locking pliers are well-known to those skilled in the art. See, for example, U.S. Pat. Nos. 5,351,585, 5,456,144 and 4,709,601, all assigned to the assignee of the present invention. Such locking pliers include an over-center toggle linkage that operates when closed to lock a movable jaw in an adjustable position with respect to a fixed jaw. Once the over-center toggle linkage has been closed, the locking pliers remains locked onto a workpiece, even if the user releases the pliers completely.
The locking pliers shown in U.S. Pat. No. 5,351,585 includes large capacity jaws and is well-suited for use in plumbing and other applications where large torques are applied to the clamped workpiece. In such applications, it would on occasion be advantageous if the locking pliers provided a larger torque arm. However, if the locking pliers shown in U.S. Pat. No. 5,351,585 were simply enlarged in scale, the enlarged pliers would be excessively heavy and awkward to use for many applications.
The present inventor is aware that pipes on occasion have been secured to the body of a locking pliers in order to provide an extended body. Such pipes are commonly known as cheater bars in other applications. Pipes of this type provide the disadvantage that they fit around the adjustment screw and that they are separate pieces. It is therefore not possible to adjust the closed position of the movable jaw with the adjustment screw when a pipe of the type described above is positioned on the body of the locking pliers.
Thus, a need presently exists for an improved locking pliers that overcomes the disadvantages discussed above.